Enhanced allogeneic skin-graft survival using sCD95L, sCD152, interleukin-10 and transforming growth factor-beta in combination, and comparison with ciclosporin

CD152 is a negative regulator of T-cell activation. The ligand of CD95, CD95L, induces apoptosis in CD95-expressing cells through activation of caspases. Interleukin (IL)-10 and transforming growth factor (TGF)-beta have been implicated in suppressing immune response. Independent treatment with the four factors can induce immunotolerance and prolong the survival of grafts.

To investigate whether joint use of murine (m)IL-10, human (h)TGF-beta and our engineered soluble extracellular part of CD152 and CD95L (sCD152, sCD95L) has a synergistic effect on immunotolerance induction in allogeneic skin transplantation.

Recipient mice were treated with sCD152, sCD95L, mIL-10 and hTGF-beta, separately or combined. The survival time of skin allografts was observed and mixed lymphocyte reactions were performed to detect the reactivity of splenic cells from recipient mice compared with splenic cells from donors or from unrelated Institute of Cancer Research mice. The levels of cytokines such as IL-2, IL-4 and interferon (IFN)-gamma, and antibodies specific for engineered sCD152 or sCD95L in serum were determined by ELISA.

Combined treatment with sCD152 and sCD95L synergistically prolonged the mean survival time (MST) of skin allografts, but the addition of mIL-10 or hTGF-beta to these did not improve MST further.

sCD152 and/or sCD95L regulate the differentiation of T-helper (Th) cells and induce the cytokine production shift of Th1-associated and Th2-associated cells. Both IFN-gamma and IL-2 were negatively correlated and IL-4 was positively correlated with skin MST. Cytokines such as IFN-gamma, IL-2 and IL-4 might function as indicators for predicting graft survival time.